To re-create: Choose two koha accounts -- I'll call them SENDER and RECEIVER. Make sure that RECEIVER has your email address. Make sure that SHARE_INVITE letter is defined for email, and contains the string <<shareurl>> 1/ Log in to the opac as user SENDER 2/ Click on 'your lists' in left menu bar 3/ Create a private list 4/ Click 'edit' 5/ Make sure that permissions for 'anyone else to add entries.', 'anyone to remove their own contributed entries.', 'anyone to remove other contributed entries.' are all set to 'Allow' (I'm not sure that this is necessary, but it's in the steps that I got from the library) 6/ Click 'Save' 7/ Click 'Share' 8/ Add the email address for RECEIVER 9/ Click 'Send' Check your email (if your test environment sends email ) or search message_queue for last entry with your email address. Navigate to the link generated by <<shareurl>> You will get a software error.
Notes found during trouble-shooting: borrowernumber is NULL in both message_queue and virtualshelfshares. I suspect that a borrowernumber must be present for private shares, but the link isn't being made between the email provided and the borrower account, but that's just a hunch.